Rick Prelinger does an excellent job in showing what his Archive is about. Something everyone who enjoys his collection show watch.

My favorite collection on the Internet Archive is Prelinger. I have used several of their films in videos I upload to youtube.

I started cruising around just to see America as it used to be, having bought an old 1900 house in a historical industrial Seattle neighborhood and becoming very interested in all facets of turn-of-the century American History. From just digging on the old images, I began to get curious as to these films' true nature. WHY were they made, really? I'm now reading "Better Living" by William Bird and learning just why Jam Handy, for instance, was being paid to produce so many films that don't overtly advertise a specific product. It's really a lot more insidious than you'd realize. Awesome stuff, and historical on tons of different levels.

An overview of the Prelinger Archives and how it came to be. This is probably my favorite site on the internet, for its films are truly social history documents, unpolluted by present-day
points of view. This is how Americans really saw themselves generations ago. Priceless material
for which we should be very grateful indeed...and to make so much of it available for free over the internet---well, all I can say is THANK YOU, THANK YOU, THANK YOU!!!

This film is a MUST for anyone who is new to the website. It tells you about what this website has to offer, and it shows some clips of films on the site...

HeÂs got a lot of films in his collection. Wonder how much he could get if he sold them on Ebay. Who cares about a bunch of old films anyways?
JUST KIDDING RICK!! I love ya! This is a MUST SEE on this site!

this short video is the essential introduction to the Prelinger Archives. After viewing it at least 6 times, I still find it most entertaining

This is a perfect introduction for anybody not already familiar with Prelinger Archives, although still quite an interesting watch for those who are familiar with either this site, or the actual Archives in New York.
Narrated (somewhat expectedly) by Mr Rick Prelinger, this film gives an overview of the archive itself, the services it provides, and a great explanation and history of Ephemeral films. It remains interesting the entire time, and features plenty of films contained in the archive.
This is worth the download purely to better grasp the idea and realisation of Prelinger Archives, no matter how much you already know, or how long you have been visiting this site.
So show your friends and family and get them involved in the Prelinger Archives too =)
Oh, and I know how to pronounce ephemeral and Prelinger now, so I'm wrapped =P